1. Technical Field of the Invention
This invention relates to telecommunication systems and, more particularly, to a system and method of providing preferential access to subscribers of localized service areas (LSAs) in a radio telecommnunications network.
2. Description of Related Art
In the Global System for Mobile Communications (GSM), business indoor systems and home zones may be operated in cooperation with a local provider of cellular service. A Localized Service Area (LSA) may be defined for the business system or home zone, and may include one or more cells. Special tariffs or special sets of service features may be provided for certain subscribers within the LSA. The cells of the LSA may be contiguous or they may be distributed. For example, one cell may be in located in one city while one or more other cells in the LSA are located in another city. As long as a single LSA-ID is utilized to identify the LSA in the network, the LSA is treated as a single logical entity.
A proposed standard called Support of Localized Service Area (SoLSA) provides that the operator of LSA may offer several alternative types of restricted access to the LSA. Under "LSA-only" access, a LSA subscriber is allowed to access the Public Land Mobile Network (PLMN) within the subscriber's allowed LSA, but is not allowed to receive or originate calls outside the LSA. Non-LSA subscribers may receive or originate calls inside or outside the LSA, provided the LSA is not an exclusive access LSA. However, a problem arises if there is not sufficient capacity available in the LSA to support both LSA subscribers and non-LSA subscribers requesting access through the LSA. In this case, non-LSA subscribers may preempt LSA subscribers who are then unable to access the network.
Under "exclusive" access, cells in the LSA are for the exclusive use of LSA subscribers. Thus, LSA subscribers may access the PLMN either inside or outside the LSA, but non-LSA subscribers are not allowed to utilize cells within the LSA. This technique, however, may result in inefficient utilization of network resources, and loss of potential revenue to the operator, if an insufficient number of LSA subscribers utilize the LSA cells.
Finally, under "preferential" access, both LSA subscribers and non-LSA subscribers may access the PLMN through the LSA, but some resources in the LSA cells are reserved to provide preferential access for LSA subscribers. Non-LSA subscribers must compete for the remaining limited resources within the LSA. For example, a bank of channels may be reserved for the exclusive use of LSA subscribers. However, this technique may also result in inefficient utilization of network resources, and loss of potential revenue to the operator, when reserved channels go unused while there is demand from non-LSA subscribers.
The problem is further complicated in the GSM system since prioritization techniques are already in place to give certain subscribers priority for system access. For example, subscribers who are capable of preempting other subscribers are assigned a property in their home location register (HLR) called a Preemption Capability Indicator (PCI). Conversely, subscribers who are vulnerable to preemption are assigned a property in the HLR called a Preemption Vulnerability Indicator (PVI). Subscribers who do not have either one of these indicators set in the HLR fall in between in the prioritization scheme. Thus, a subscriber who does not have either indicator set may be,preempted by a subscriber with PCI, but may still preempt a subscriber with PVI set.
In the context of a LSA, a problem arises in granting access to the LSA when a non-LSA subscriber enters the LSA with PCI set. Under existing standards, this non-LSA subscriber can then preempt LSA subscribers who do not have PCI set, even in their own LSA. Thus, LSA subscribers may lose their preferential treatment.
It would be advantageous to have a system and method of providing preferential access to subscribers of LSAs that efficiently utilizes the resources of the network, is compatible with the SoLSA standard, and overcomes the problem presented by other prioritization techniques in the GSM system. The present invention provides such a system and method.